Emptying A Radiator

[PringlesQueen]

I need to fit a new thermostatic valve onto my radiator. Does anybody know roughly how much water is held in a radiator? It is about 4ft long, has two panels and lots of fins inside.
Many thanks

[ChillDoubt]

Shouldn't be more than a pint and a half (rough guesstimate). Video should prove helpful:

http://www.youtube.com/watch?v=5dP2S-Mbh0E

[ChillDoubt]

This is a bit more specific:

http://www.youtube.com/watch?v=2aLBOzqvosE

[PringlesQueen]

Thank you ChillDoubt - very helpful. I never thought of looking on YouTube!

[ChillDoubt]

No problem.

Which one deserves the Best Answer slection do you think?

(Hint, hint!)

Just kidding. Did you manage the job alright?

[BRIGHT SPARK]

Pringles.......you will need to drain the system to fit a trv......not just the radiator.

[jomifl]

You don't even need to drain the rad.

[BRIGHT SPARK]

jom......you do to change the valve.

[jomifl]

If you do decide to drain the system remember to put inhibitor in before you fill it up. Unless of course you have saved the water + inhibitor that you drained out.

[BRIGHT SPARK]

come on jom.......how do you change the valve without draining some of the system :-)...or getting wet...or using a freeze collar.

[jomifl]

If you slacken the nuts at each end of the rad enough to pivot it down to the floor you can remove the trv and replace it with the loss of a few drops of water. Just make sure that the new valve is the same size and has the same fittings. Put a tray under the work area and have some old towels handy.

[BRIGHT SPARK]

Could you send us a video :-)

[jomifl]

Water won't run out unlesss it is replaced with air..it ain't rocket science. If the system isn't a combi boiler you will have to close the replenishment/expansion tank valve.

[jomifl]

No, my video camera got flooded :o)

[BRIGHT SPARK]

Lets just hope Pringles does,nt have cream carpets!

[The Builder]

Jom... even with the rad pivoted down, the body of the old TRV is still connected to the supply tail that comes up out of the floor.

Personally, for one rad, I would freeze the flow and return to that particular rad ............ unless you're due for a flush.

[jomifl]

Obviously cream carpets put a different complexion on it:o)

[Nottm_George]

So can you take the valve off you will have to drain the system down, it's only if you have to take the rad off you can use the valves to stop the water draining off from the rest of the system.